### History of the event

Evolution of the sciences that led to the emergence of computer science

If IT as such has only existed for a few decades, its origins come from many fields, some of which go back to a very long time. Examples include abacuses and counting abacuses. These are the first instruments to assist in calculations. We will also see that the history of numeration is not without interest to help us understand position numeration and more particularly binary codes.

- Calculating machines
- Abacus and abacus
- Chinese abacus

The counter abacus, which originated in Asia, where it still has enthusiasts, is said to be the first “calculating machine”. It is actually only a device for recording calculations. Although very basic, this instrument already has some instructive features. We use it to illustrate what the position number is: the abacus has several rods, each corresponding to the position of a number (units, tens, hundreds, thousands, etc.) On these rods are threaded balls whose position forms a code ranging from 0 to 9 or from 0 to 10 depending on the abacus models. The abacus facilitate the calculation by “displaying” and therefore “memorizing” the result of the last operation.

**Roman Abaque**

Roman abacuses were also instruments to assist in the representation, memorization and manipulation of numbers. The balls of the abacus are replaced here by stones (calculated in Latin) placed in parallel notches each representing multiples of 1, 10, 100, 1000 etc.

**Statue of Al-khwarizmi**

For us who are used to Arabic numerals, it is strange to note that it took our ancestors so long to adopt number writing based on position numbering, as abacus and abacus did. The Romans, for example, were obliged to change the signs to write the number 1 according to whether it represented a unit (I) a dozen (X) a hundred (C) or a thousand (M). Imagine how difficult it must have been to make written calculations under these conditions.

The position number (as well as the number zero) would have been imagined in India in the 4th or 5th century; it was adopted by the Arab mathematician Al-khawarizmi around the year 820 and imposed itself in the West after the 12th or 13th century crusades.